Bad Gas Mileage and little power?

Hey guys.. I just ran a tank of fuel through the new truck.. Its a 1999 SR5 5speed with the i4

I got 357km and drank 56liters of fuel (driving mainly highway with a few short city trips.. 2wd mainly but did need to use 4x4 for prolly 10% of the 357km)

I picked up new plugs from Toyota and got a new air filter im going to hopefully get around to doing it one day this week when its a bit nicer outside (-21 right now).. I plan on seafoaming it first and then do the plugs, oil, and air filter (although the filter could be thrown in anytime)..

As far as power goes im not too sure what to expect from this engine.. But when in 4x4 on the highway (100-110km/h) I cannot maintain speed in 5th and I need to be in 4th.. When in 2wd it seems ok and I only need to downshift during inclines.. Just curious if this is standard or if I may have some issues..

Any insight into this?

 

Those short city trips @ -21C can kill your fuel economy. The engine is running rich for the entire trip. And, then consider that you're using winter gas probably with high ethanol content.

You need to go through a few more tanks and also compare with warmer temperatures before you'll really know what's happening.

Addition: why are you in 4WD on the highway at 110km/h? If you're going that fast, you probably can see bare pavement (at least occasionally), which means you shouldn't be using 4WD if you enjoy having a transfer case that works.

 

Has the check engine light came on? If so, check it out and see if it is line with my issue that I dealt with.

My power and fuel economy suffered greatly as my truck reached around 300k miles. The check engine light came on the upstream oxygen sensor had went bad. When an O2 sensor goes out it will throw extra fuel into the manifold. The unburnt extra fuel will eventually ruin your catalytic converter. Once the converter is ruined you power will decrease dramatically and you will burn more fuel as well.